I have three PCs running Win 7 and am familiar with many more. None of them exhibit this problem - indeed, all are remarkably stable.
This suggests that your problem is specific. Can you provide more information of when it happens or is it truly random? Does it only happen when you select or right click a file or folder? If so, what type(s) of file? What anti-virus are you running?
Without any info, this is a real shot in the dark but my money would be on your graphics driver or a registry problem. The latter is easily sorted, the former a bit trickier.